<!DOCTYPE html>
<html lang="en">

<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>Recording</title>
 <link rel="stylesheet" href="./index.css">
</head>

<body>
 <section class="calculator">
  <form>
   <input type="text" name="" id="" class="screen">
  </form>
  <div class="buttons">
   <!-- yellow -->
   <button type="button" class="btn btn-yellow" data-num="*">*</button>
   <button type="button" class="btn btn-yellow" data-num="/">/</button>
   <button type="button" class="btn btn-yellow" data-num="-">-</button>
   <button type="button" class="btn btn-yellow" data-num="+">+</button>
   <!-- grey buttons -->
   <button type="button" class="btn btn-grey" data-num=".">.</button>
   <button type="button" class="btn btn-grey" data-num="9">9</button>
   <button type="button" class="btn btn-grey" data-num="8">8</button>
   <button type="button" class="btn btn-grey" data-num="7">7</button>
   <button type="button" class="btn btn-grey" data-num="6">6</button>
   <button type="button" class="btn btn-grey" data-num="5">5</button>
   <button type="button" class="btn btn-grey" data-num="4">4</button>
   <button type="button" class="btn btn-grey" data-num="3">3</button>
   <button type="button" class="btn btn-grey" data-num="2">2</button>
   <button type="button" class="btn btn-grey" data-num="1">1</button>
   <button type="button" class="btn btn-grey" data-num="0">0</button>
   <button type="button" class="btn-equal btn-grey">=</button>
   <button type="button" class="btn-clear btn-grey">C</button>
  </div>
 </section>
 <script src="./index.js"></script>
</body>

</html>